We now have the second case of an individual showing no traces of the virus after stem cell treatment.
The world is inching closer towards a breakthrough on HIV/AIDS—no trace of the virus replicating was detected in a HIV+ person (identity not disclosed) who received a stem cell transplant that replaced her/his white blood cells with HIV-resistant variants. This is the second time such a line of treatment has thrown up results that fuel optimism in the search for a cure for HIV. The first time was in 2008, when Timothy Ray Brown (who disclosed his identity in 2010) was reported to show no trace of HIV replication in his body following a stem cell transplant. Both Brown and the person in the present instance were suffering from cancer that did not respond to chemotherapy. In both cases, a bone marrow transplant—marrow is where haematopoietic stem cells that can differentiate into any kind of blood cells (RBCs, WBCs, platelets) are formed—was the only cure; this involved killing off the recipient’s own marrow and blood cells, which would then be replaced by the donor’s. In the present instance, a team of doctors/medical researchers, led by Ravindra Gupta, an infectious disease physician at the University of Cambridge, selected a donor who had a homozygous (trait inherited from both maternal and paternal gene) mutation in the CCR5 gene that makes people resistant to HIV, instead of choosing any suitable donor. This was also done in Brown’s case. The CCR5 gene codes for a receptor protein on the surface of WBCs to which HIV binds and attacks the cells. A deletion in the gene interferes with receptors’ functioning and prevents HIV binding. While Brown has shown no trace of the virus so far after stopping anti-retroviral drugs—the mainstay of HIV/AIDS management—the new subject stopped her/his anti-retroviral treatment 18 months earlier (16 months after the transplant) and is still HIV-free. Nature reports that 1% of people of European descent exhibit a homozygous anti-HIV CCR5 mutation, and are thus resistant to HIV.
While Gupta and others are choosing to be cautious about declaring the patient cured, the latest case shows that Brown’s successful treatment can be replicated. Between Brown’s treatment and the second case, many aspects of the entire course of treatment have become less aggressive and, therefore, more patient-friendly. There are, of course, some factors to consider before this can be celebrated as the HIV-cure the world has been waiting for. First, this line of treatment is prescribed for certain cancers, and not for HIV or any other related complications—which means, considering the risks of fatal complications in the procedure, it may not be ethical to advise this to get rid of HIV. The costs attached are another hurdle—while governments have focused on anti-retrovirals as the main weapon in public health’s anti-HIV/AIDS arsenal, and have managed to keep the costs low, until the CCR5 treatment line becomes more driven by market than research, costs of stem cell therapy to fight HIV/AIDS are unlikely to fall.
Against the backdrop of Chinese researcher He Jiankui’s violation of gene-editing ethics involving the CCR5 mutation, the world must still navigate regulatory grey areas. However, given Sustainable Development Goal 3.3 calls for fighting, amongst other diseases, HIV/AIDS, the latest development is a seminal one. It lays the path for further research and policy deliberations. How important this is can be gleaned from the fact that, as per UNAIDS, of the 36.9 million worldwide living with HIV/AIDS in 2017, only 21.7 million were able to access anti-retroviral therapy and 1.8 million had been newly infected (infection detected that year). India, in 2016, reported 80,000 new infections amongst a population of 2.1 million living with HIV/AIDS—of the overall figure, just under half were accessing anti-retroviral therapy.